Roger, I totally agree with starting out at the recommended CG of 4 7/8" which is nose heavy. As far as the tank goes as a form of ballast it is not reliable due to change as fuel draws. Let me specify that the variations are more noticible in advanced stages with a more aft CG. My feelings on a remote tank placement make the planes characteristics more consistant. With the tank on the CG the battery can now go forward to obtain 4 7/8" After becoming prolific with the model and a desire for more aerobatic performance comes into play the battery can now start to move aft to a more tail heavy attitude. With this set up, full or empty, the tank does not effect the CG. Joe